The project is designed to meet a demand by the research community for small animal models for the study of those human diseases with major health implications. Developmental efforts have focused on rat models of rheumatoid arthritis, insulin independent diabetes mellitus and chemical addictions. In mice, the primary effort has been directed towards developing models of immunodeficiency which are beginning to find broad usage in those areas of biomedical research in which the immune system plays an important role. Other areas which are either being planned or initiated consist of characterizing selected closed breeding groups of rats for a variety of behavioral traits in preparation for studies of the molecular basis for these traits.